After a few notable delays, Microsoft finally has shipped the latest beta version of Windows XP Service Pack 2, which the company has touted as a major milestone toward developing more secure software.

The second "release candidate" of the service pack, which more resembles an upgrade to the 2-year-old operating system, was made available last week.

Microsoft says the final release of the service pack is expected this summer. It originally was planned for the first half of this year.

The company released the first beta of XP SP2 in December, followed by Release Candidate 1 in March. Release Candidate 2 was originally planned for last month, but Microsoft was said to have delayed the release to fix some bugs and correct some compatibility issues. For months, Microsoft has warned corporate users that SP2 will break some applications. The company has implored users to thoroughly test applications against the service pack.

The application issue is most prominent in the Windows Firewall. The firewall is turned on by default and will disrupt communication for existing applications, such as remote administration and patch management tools, performance monitors and other tools that communicate via file-and-print sharing channels, hard-drive shares that operate over specific ports, and peer-to-peer and file-sharing programs.

The firewall can be configured to permit those communications, but users will trade security for those conveniences.

Also, new security restrictions placed on Remote Procedure Call and Distributed Component Object Model services, which are often exploited by worms and viruses, could choke applications. New memory protection features also might hamper performance and stifle code generated by just-in-time compilers.

Those issues and others, such as recurring exploits of the Windows operating system, have generated a lot of hubbub over XP SP2.

"We are not lying in wait for this service pack," says Roy Haschenburger, president of Alternative Computers, an IT contractor to government organizations in Denver. "It's a non-issue right now. We have tested it and haven't seen any real positive or negative impact. People are concerned with day-to-day issues and such things as worms, rather than worrying about Microsoft coming up with something that might improve the [operating system] and make it more robust and stable."